Juglans nigra

"Black Walnut" redirects here. For other uses, see Black Walnut (disambiguation).

Eastern black walnut
Leaves and fruit
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Fagales
Family:	Juglandaceae
Genus:	Juglans
Species:	J. nigra
Binomial name
Juglans nigra L.

Juglans nigra, the Eastern black walnut, a species of flowering tree in the walnut family, Juglandaceae, is native to eastern North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central Texas. Isolated wild trees in the upper Ottawa Valley may be an isolated native population or may have derived from planted trees.

The black walnut is a large deciduous tree attaining heights of 30–40 metres (98–130 ft). Under forest competition, it develops a tall, clear bole; the open-grown form has a short bole and broad crown. The bark is grey-black and deeply furrowed. The pith of the twigs contains air spaces. The leaves are alternate, 30–60 cm long, odd-pinnate with 15–23 leaflets, with the largest leaflets located in the center, 7–10 cm long and 2–3 cm broad. The male flowers are in drooping catkins 8–10 cm long, the female flowers are terminal, in clusters of two to five, ripening during the autumn into a fruit (nut) with a brownish-green, semifleshy husk and a brown, corrugated nut. The whole fruit, including the husk, falls in October; the seed is relatively small and very hard. The tree tends to crop more heavily in alternate years.

While its primary native region is the Midwest and east-central United States, the black walnut was introduced into Europe in 1629. It is cultivated there and in North America as a forest tree for its high-quality wood. More nuts are produced by open-grown trees. Black walnut is more resistant to frost than the English or Persian walnut, but thrives best in the warmer regions of fertile, lowland soils with a high water table. It is a light-demanding species. The wood is used to make furniture, flooring, and rifle stocks, and oil is pressed from the seeds. Nuts are harvested by hand from wild trees. About 65% of the annual wild harvest comes from the U.S. state of Missouri, and the largest processing plant is operated by Hammons Products in Stockton, Missouri. The black walnut nutmeats are used as an ingredient in food, while the hard black walnut shell is used commercially in abrasive cleaning, cosmetics, and oil well drilling and water filtration.

Where the range of J. nigra overlaps that of the Texas black walnut J. microcarpa, the two species sometimes interbreed, producing populations with characteristics intermediate between the two species.

Uses

{{Nutritional value | name = Walnut, black (J. nigra)

what the heck are black walnuts there creepy little walnut. just die a nut a color and it will be done!!!!

Pests

Maggots (larvae of Rhagoletis completa and Rhagoletis suavis) in the husk are common, though more a nuisance than a serious problem for amateurs, who may simply remove the affected husk as soon as infestation is noticed. The maggots develop entirely within the husk, thus the quality of the nutmeat is not affected. However, infestations of maggots are undesirable because they make the husk difficult to remove and are unsightly. Maggots can be serious for commercial walnut growers, who tend to use chemical treatments to prevent damage to the crop. Some organic controls also exist, such as removing and disposing of infested nuts.

The walnut curculio (Conotrachelus retentus) grows to 5 mm long as an adult. The adult sucks plant juices through a snout. The eggs are laid in fruits in the spring and summer. Many nuts are lost due to damage from the larvae, which burrow through the nut shell.

Codling moth (Cydia pomonella) larvae eat walnut kernels, as well as apple and pear seeds.

A disease complex known as thousand cankers disease has been threatening black walnut in several western states. This disease has recently been discovered in Tennessee, and could potentially have devastating effects on the species in the eastern United States.

Toxicity

The roots, nut husks, and leaves secrete a substance into the soil called juglone that is a respiratory inhibitor to some plants. A number of other plants (most notably white birch) are also poisoned by juglone, and should not be planted in close proximity to a black walnut. The plant can cause contact dermatitis in humans. Horses are susceptible to laminitis from exposure to black walnut wood in bedding.

Big tree

The largest known living black walnut tree is on Sauvie Island, Oregon.

The national champion black walnut is on a residential property in Sauvie Island, Oregon. It is 8 feet 7 inches (2.62 m) diameter at breast height and 112 feet (34 m) tall, with a crown spread of 144 feet (44 m).

References

• Hoadley, B. (1990). Identifying Wood: Accurate Results with Simple Tools. Taunton Press. p. 240 pages. ISBN 0-942391-04-7. 
• Dirr, M. A. (1998). Manual of Woody Landscape Plants. Stipes Publishing. ISBN 0-87563-795-7
• Petrides, G. A. and Wehr, J. (1998). Eastern Trees. Houghton Mifflin Company. ISBN 0-395-90455-2
• Williams, Robert D. Juglans nigra L. In: USDA Forest Service: Silvics of Trees of North America. Volume 2: Hardwoods.

See also

• English walnut, Persian walnut
• Taxonomy of walnut tree varieties

External links

External identifiers for Juglans nigra
EOL	594611
ITIS	19254
NCBI	16719
Also found in: Wikispecies

• Guide to “Growing Black Walnuts for Nut Production” University of Missouri Center for Agroforestry
• Walnut council
• Black Walnut Cultivars
• Extensive information about black walnuts
• Flora of North America: J. nigra RangeMap:
• Juglans nigra images at bioimages.vanderbilt.edu
• Set of Black Walnut ID photos and range map
• Harvesting Black Walnuts
• Home Production of Black Walnut Nutmeats
• Growing Black Walnut
• Black Walnut crackers
• Black Walnut Diagnostic photos: tree, leaves, bark and fruit
• The Hiker's Notebook
• Black Walnut Toxicity study
• Images, diseases, galls and fungi on treetrees.com